Knowledge

Inharmonicity

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more sonorous. The result is that pianos tuned by ear and immediately checked with a machine tend to vary from one degree to another from the purely theoretical semitone (mathematically the 12th root of two) due to human error and perception. (If pleasing the ear is the goal of an aural tuning, then pleasing the math is the goal of a machine tuning.) This is thought to be because strings can vary somewhat from note to note and even from neighbors within a unison. This non-linearity is different from true falseness where a string creates false harmonics and is more akin to minor variations in string thickness, string sounding length or minor bridge inconsistencies.
40: 164:, and length. For instance, a stiff string under low tension (such as those found in the bass notes of small upright pianos) exhibits a high degree of inharmonicity, while a thinner string under higher tension (such as a treble string in a piano) or a more flexible string (such as a gut or nylon string used on a guitar or harp) will exhibit less inharmonicity. A wound string generally exhibits less inharmonicity than the equivalent solid string, and for that reason wound strings are often preferred. 273:
The inharmonicity in guitar strings can "cause stopped notes to stop sharp, meaning they will sound sharper both in terms of pitch and beating, than they "should". This is distinct from any temperament issue." Even if a guitar is built so that there are no "fret or neck angle errors, inharmonicity can make the simple approach of tuning open strings to notes stopped on the fifth or fourth frets" unreliable. Inharmonicity also demands that some of the "octaves may need to be compromised minutely."
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sophisticated devices allow a technician to make custom inharmonicity measurements—simultaneously considering all partials for pitch and volume to determine the most appropriate stretch to employ for a given instrument. Some include an option to simply record a tuning that a technician has completed by ear; the technician can then duplicate that tuning on the same piano (or others of similar make and model) more easily and quickly.
175:, this means that the frequency of the harmonics increases linearly with the mode number. The added dispersion due to the stiffness, which is most prevalent in the thick bass strings, means that as the frequency increases, so too does the wave speed in the string. The result is that modes of the stiff string are no longer perfectly harmonic. 129:, the overtones are close to—or in some cases, quite exactly—whole number multiples of the fundamental frequency. Any departure from this ideal harmonic series is known as inharmonicity. The less elastic the strings are (that is, the shorter, thicker, smaller tension or stiffer they are), the more inharmonicity they exhibit. 297:
technique. However, this inharmonicity disappears when the strings are bowed, because the bow's stick-slip action is periodic, driving all of the resonances of the string at exactly harmonic ratios even if it has to drive them slightly off their natural frequency. As a result, the operating mode of a
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Some performers choose to focus the tuning towards the key of the piece, so that the tonic and dominant chords will have a clear, resonant sound. However, since this compromise may lead to muddy-sounding chords in sections of a piece that stray from the main key (e.g., a bridge section that modulates
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between tones. Piano tuners must deal with the inharmonicity of piano strings, which is present in different amounts in all of the ranges of the instrument, but especially in the bass and high treble registers. The result is that octaves are tuned slightly wider than the harmonic 2:1 ratio. The exact
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The issues surrounding setting the stretch by ear vs machine have not been settled; machines are better at deriving the absolute placement of semitones within a given chromatic scale, whereas non-machine tuners prefer to adjust these locations preferentially due to their temptation to make intervals
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counteracts the natural inharmonicity of the string or air column and causes the overtones to lock precisely onto integer multiples of the fundamental pitch, even though these are slightly different from the natural resonance points of the instrument. For this reason, a single tone played by a bowed
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In 1943, Schuck and Young were the first scientists to measure the spectral inharmonicity in piano tones. They found that the spectral partials in piano tones run progressively sharp—that is to say, the lowest partials are sharpened the least and higher partials are progressively sharpened further.
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in the 1980s reached the mass market, it did not spell the end of tuning problems for guitarists. Even if an electronic tuner indicates that the guitar is "perfectly" in tune, some chords may not sound in tune when they are strummed, either due to string inharmonicity from worn or dirty strings, a
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While piano tuning is normally done by trained technicians, guitars such as acoustic guitars, electric guitars, and electric bass guitars are usually tuned by the guitarist themselves. When a guitarist tunes a guitar by ear, they have to take both temperament and string inharmonicity into account.
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Music harmony and intonation depends strongly on the harmonicity of tones. An ideal, homogeneous, infinitesimally thin or infinitely flexible string or column of air has exact harmonic modes of vibration. In any real musical instrument, the resonant body that produces the music tone—typically a
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Because of the problem of inharmonicity, electronic piano tuning devices used by piano technicians are not designed to tune according to a simple harmonic series. Rather, the devices use various means to duplicate the stretched octaves and other adjustments a technician makes by ear. The most
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Inharmonicity is not necessarily unpleasant. In 1962, research by Harvey Fletcher and his collaborators indicated that the spectral inharmonicity is important for tones to sound piano-like. They proposed that inharmonicity is responsible for the "warmth" property common to real piano tones.
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misplaced fret, a mis-adjusted bridge, or other problems. Due to the range of factors in play, getting a guitar to sound in tune is an exercise in compromise. "Worn or dirty strings are also inharmonic and harder to tune", a problem that can be partially resolved by cleaning strings.
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Another factor that can cause problems is the presence of rust on the strings or dirt in the windings. These factors can slightly raise the frequency of the higher modes, resulting in more inharmonicity.
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string, wire, or column of air—deviates from this ideal and has some small or large amount of inharmonicity. For instance, a very thick string behaves less as an ideal string and more like a
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sounded more natural when some inharmonicity was introduced. In general, electronic instruments that duplicate acoustic instruments must duplicate both the inharmonicity and the resulting
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in a piano tuning varies from piano to piano and even from register to register within a single piano—depending on the exact inharmonicity of the strings involved.
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of waves in a stiff string. In an ideal flexible string, the wave speed is constant as a function of frequency. Looking at the resonant frequency of a
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to minimize out-of-tuneness in the intervals and chords that will be played, and in terms of dealing with inharmonicity. For more information,
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a semitone down), some performers choose to make a broader compromise, and "split the difference" so that all chords will sound acceptable.
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Other stringed instruments such as the violin, viola, cello, and double bass also exhibit inharmonicity when notes are plucked using the
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However, when a string is struck or plucked, as with a piano string that is struck by its hammer, a violin string played
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Acoustically, a note perceived to have a single distinct pitch in fact contains a variety of additional overtones. Many
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Percussion bars, such as xylophone, are hung at ≈2/9 and ≈7/9 length, and struck at 1/2 length, to reduce inharmonicity.
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B. C. J. Moore, R.W. Peters, and B. C. Glasberg, “Thresholds for the detection of inharmonicity in complex tones,”
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F. Scalcon, D. Rocchesso, and G. Borin, “Subjective evaluation of the inharmonicity of synthetic piano tones,” in
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bowed string playing a steady note is a compromise among the tunings of all of the (slightly inharmonic)
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string instrument, brass instrument, or reed instrument does not necessarily exhibit inharmonicity.
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https://web.archive.org/web/20071015200222/http://www.amarilli.co.uk/guitar/howto.asp
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When strobe tuners became available in the 1970s, and then inexpensive
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Acoustical Society of America - Large grand and small upright pianos
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How harmonic are harmonics? by Joe Wolfe, accessed 29 June 2008
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Proceedings of the Society for Music Perception and Cognition
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Comparing harmonic (top) and inharmonic (bottom) waveforms.
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Piano tuning is a compromise—both in terms of choosing a
568:"Nonlinear Dynamics and Chaos in Musical Instruments" 219:, the technician sometimes listens for the sound of " 633:, MIT, Cambridge, Massachusetts, July - August 1997. 152:, or a guitar string that is plucked by a finger or 189: 167:The physical origin of this inharmonicity is the 1025: 490:The Indian Musical Drums by Sir C V Raman 1930 185:Piano Acoustics - Inharmonicity and Piano Size 652: 117:However, in stringed instruments such as the 562: 560: 659: 645: 589: 587: 585: 583: 615:vol. 77, no. 5, pp. 1861–1867, 1985. 557: 510:by Alexander Galembo and Lola L. Cuddy] 106:, create complex and inharmonic sounds. 83:multiples of the fundamental frequency ( 54: 46: 38: 26: 580: 211:Inharmonicity leads to stretched tuning 35:(dashed gray lines indicate harmonics). 1026: 317: 640: 474: 472: 470: 468: 533:The Cambridge companion to the piano 132:When a string is bowed or tone in a 13: 605: 465: 125:, or in some Indian drums such as 14: 1050: 141: 1008: 1007: 720: 613:Journal of the Acoust. Soc. Am., 288: 622:ICMC’98, pp. 53–56, 1998. 546: 525: 513: 494: 483: 190:Sound quality of inharmonicity 1: 666: 519:Matti A. Karjalainen (1999). 458: 207:of the original instruments. 140:or lips, a phenomenon called 620:Proc. Int. Comp. Music Conf. 566:Neville H. Fletcher (1994). 199:According to their research 7: 595:"What is a Sound Spectrum?" 577:. Complexity International. 436: 67:is the degree to which the 10: 1055: 388:Plucked string instruments 182: 173:string with two fixed ends 15: 1003: 955: 884: 781: 739: 715: 674: 267: 215:When pianos are tuned by 178: 77:partials or partial tones 31:Inharmonic spectrum of a 329:Bowed string instruments 16:Not to be confused with 684:Architectural acoustics 531:Rowland, David (1998). 201:synthesized piano tones 136:initiated by vibrating 771:Fletcher–Munson curves 766:Equal-loudness contour 676:Acoustical engineering 409:Approximately harmonic 60: 52: 44: 36: 907:Hermann von Helmholtz 805:Fundamental frequency 709:Sympathetic resonance 230:octaves are stretched 94:instruments, such as 58: 50: 42: 30: 927:Werner Meyer-Eppler 837:Missing fundamental 318:List of instruments 810:Frequency spectrum 573:2009-10-17 at the 506:2012-02-09 at the 429:Untuned percussion 323:Perfectly harmonic 61: 53: 45: 43:Harmonic spectrum. 37: 1021: 1020: 983:Musical acoustics 815:harmonic spectrum 347:Brass instruments 300:string resonances 278:electronic tuners 1046: 1011: 1010: 912:Carleen Hutchins 844:Combination tone 731: 724: 704:String vibration 661: 654: 647: 638: 637: 599: 598: 591: 578: 564: 555: 550: 544: 529: 523: 517: 511: 498: 492: 487: 481: 476: 415:Tuned percussion 308:reed instruments 205:stretched tuning 1054: 1053: 1049: 1048: 1047: 1045: 1044: 1043: 1024: 1023: 1022: 1017: 999: 951: 942:D. Van Holliday 880: 849:Mersenne's laws 783:Audio frequency 777: 741:Psychoacoustics 735: 734: 727: 713: 670: 665: 625:A. Galembo and 608: 606:Further reading 603: 602: 593: 592: 581: 575:Wayback Machine 565: 558: 551: 547: 530: 526: 518: 514: 508:Wayback Machine 499: 495: 488: 484: 477: 466: 461: 439: 382:Nearly harmonic 365:Reed aerophones 320: 291: 270: 251:Piano acoustics 213: 192: 187: 181: 134:wind instrument 85:harmonic series 75:(also known as 25: 12: 11: 5: 1052: 1042: 1041: 1039:Musical tuning 1036: 1019: 1018: 1016: 1015: 1004: 1001: 1000: 998: 997: 996: 995: 990: 980: 975: 970: 965: 959: 957: 956:Related topics 953: 952: 950: 949: 944: 939: 937:Joseph Sauveur 934: 929: 924: 922:Marin Mersenne 919: 914: 909: 904: 899: 894: 888: 886: 882: 881: 879: 878: 873: 872: 871: 861: 856: 851: 846: 841: 840: 839: 834: 829: 819: 818: 817: 807: 802: 797: 791: 789: 779: 778: 776: 775: 774: 773: 763: 762: 761: 756: 745: 743: 737: 736: 733: 732: 725: 717: 716: 714: 712: 711: 706: 701: 696: 691: 686: 680: 678: 672: 671: 664: 663: 656: 649: 641: 635: 634: 623: 616: 607: 604: 601: 600: 579: 556: 545: 524: 512: 493: 482: 463: 462: 460: 457: 456: 455: 450: 445: 438: 435: 434: 433: 432: 431: 424: 420: 419: 418: 417: 410: 406: 405: 404: 403: 383: 379: 378: 377: 376: 362: 344: 324: 319: 316: 290: 287: 269: 266: 212: 209: 191: 188: 183:Main article: 180: 177: 79:) depart from 9: 6: 4: 3: 2: 1051: 1040: 1037: 1035: 1032: 1031: 1029: 1014: 1006: 1005: 1002: 994: 991: 989: 986: 985: 984: 981: 979: 976: 974: 971: 969: 966: 964: 961: 960: 958: 954: 948: 945: 943: 940: 938: 935: 933: 932:Lord Rayleigh 930: 928: 925: 923: 920: 918: 915: 913: 910: 908: 905: 903: 902:Ernst Chladni 900: 898: 895: 893: 890: 889: 887: 883: 877: 874: 870: 867: 866: 865: 864:Standing wave 862: 860: 857: 855: 852: 850: 847: 845: 842: 838: 835: 833: 832:Inharmonicity 830: 828: 825: 824: 823: 820: 816: 813: 812: 811: 808: 806: 803: 801: 798: 796: 793: 792: 790: 788: 784: 780: 772: 769: 768: 767: 764: 760: 757: 755: 752: 751: 750: 747: 746: 744: 742: 738: 730: 726: 723: 719: 718: 710: 707: 705: 702: 700: 699:Soundproofing 697: 695: 694:Reverberation 692: 690: 687: 685: 682: 681: 679: 677: 673: 669: 662: 657: 655: 650: 648: 643: 642: 639: 632: 628: 624: 621: 617: 614: 610: 609: 596: 590: 588: 586: 584: 576: 572: 569: 563: 561: 554: 549: 542: 541:0-521-47986-X 538: 534: 528: 522: 516: 509: 505: 502: 497: 491: 486: 480: 475: 473: 471: 469: 464: 454: 451: 449: 448:Pseudo-octave 446: 444: 443:Anharmonicity 441: 440: 430: 427: 426: 425: 422: 421: 416: 413: 412: 411: 408: 407: 401: 397: 393: 389: 386: 385: 384: 381: 380: 374: 370: 366: 363: 360: 356: 352: 348: 345: 342: 338: 334: 330: 327: 326: 325: 322: 321: 315: 313: 309: 305: 301: 296: 286: 282: 279: 274: 265: 261: 259: 258: 253: 252: 246: 241: 237: 233: 231: 226: 222: 218: 208: 206: 202: 196: 186: 176: 174: 170: 165: 163: 159: 155: 151: 146: 143: 139: 135: 130: 128: 124: 120: 115: 113: 107: 105: 101: 97: 93: 88: 86: 82: 78: 74: 70: 66: 65:inharmonicity 57: 49: 41: 34: 29: 23: 22:Anharmonicity 19: 18:Enharmonicity 947:Thomas Young 897:Jens Blauert 885:Acousticians 831: 630: 619: 612: 548: 527: 515: 496: 485: 423:Not harmonic 310:such as the 292: 289:Mode-locking 283: 275: 271: 262: 257:Piano tuning 255: 248: 242: 238: 234: 217:piano tuners 214: 197: 193: 166: 147: 142:mode-locking 131: 116: 108: 89: 64: 62: 917:Franz Melde 892:John Backus 876:Subharmonic 729:Spectrogram 453:Subharmonic 396:harpsichord 304:human voice 245:temperament 69:frequencies 1028:Categories 978:Ultrasound 968:Infrasound 754:Bark scale 535:, p. 106. 459:References 169:dispersion 92:percussion 63:In music, 1034:Acoustics 859:Resonance 759:Mel scale 689:Monochord 668:Acoustics 295:pizzicato 225:roughness 162:stiffness 150:pizzicato 73:overtones 1013:Category 854:Overtone 822:Harmonic 627:L. Cuddy 571:Archived 504:Archived 437:See also 373:clarinet 359:trombone 312:clarinet 154:plectrum 112:cylinder 100:tam-tams 800:Formant 351:trumpet 306:and in 228:amount 221:beating 158:tension 96:cymbals 993:Violin 827:Series 539:  392:guitar 375:, ...) 361:, ...) 343:, ...) 333:violin 268:Guitar 179:Pianos 123:guitar 121:, and 119:violin 104:chimes 102:, and 988:Piano 973:Sound 787:pitch 749:Pitch 337:cello 127:tabla 81:whole 963:Echo 869:Node 795:Beat 785:and 537:ISBN 402:...) 400:harp 369:oboe 355:horn 341:erhu 254:and 249:see 138:reed 33:bell 87:). 71:of 20:or 1030:: 582:^ 559:^ 467:^ 398:, 394:, 371:, 357:, 353:, 339:, 335:, 314:. 260:. 160:, 98:, 660:e 653:t 646:v 597:. 543:. 390:( 367:( 349:( 331:( 24:.

Index

Enharmonicity
Anharmonicity

bell



frequencies
overtones
partials or partial tones
whole
harmonic series
percussion
cymbals
tam-tams
chimes
cylinder
violin
guitar
tabla
wind instrument
reed
mode-locking
pizzicato
plectrum
tension
stiffness
dispersion
string with two fixed ends
Piano Acoustics - Inharmonicity and Piano Size

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